Masimo cyberattack slowed manufacturing at the medical device maker

Masimo Corporation, a California maker of patient monitoring equipment including pulse oximeters, disclosed a cybersecurity incident in a Form 8-K filed with the US Securities and Exchange Commission on 6 May 2025. The company said it had identified unauthorised activity on its on-premise network on 27 April 2025.

Masimo activated its incident response plan, proactively isolated the affected systems and brought in third-party cybersecurity specialists to assist with investigation and recovery. It reported the incident to law enforcement and said it was coordinating its response with investigators.

The containment work carried an operational cost. Masimo said some of its manufacturing facilities were running below normal levels and that its ability to process, fulfil and ship customer orders had been temporarily affected. The company said the incident appeared to affect only its on-premise IT environment and that its cloud-based systems did not appear to have been affected.

No ransomware group publicly claimed the attack, and Masimo said it was not in a position to confirm the extent of any data theft while the investigation continued. The company later reported that key systems had been restored, with manufacturing back at near full capacity and order taking, distribution and shipping fully operational by 28 May 2025. It maintained its fiscal 2025 revenue guidance and said it expected cyber insurance to cover remediation costs.